1. Field of the Invention
The present invention relates to a head assembly suitable for attaining higher recording density of a magnetic disk drive apparatus used in such as a storage apparatus of a computer, to a magnetic disk drive apparatus with the head assembly, and to a rotation or turning mechanism.
2. Description of the Related Art
Recently, the recording density of a magnetic disk used in a magnetic disk drive apparatus becomes increasingly higher. Such magnetic disk drive apparatus has generally a slider on which a magnetic head for recording and/or reproducing data in/from the magnetic disk is mounted. The slider is supported by a head support mechanism. The head support mechanism has a head-actuator arm to which the slider is attached. This head-actuator arm is able to turn by a voice coil motor (VCM). Positioning of the magnetic head mounted on the slider to an arbitrary position on the magnetic disk is performed by controlling the VCM.
In order to record data on a magnetic disk with much higher density, it is required to make the positioning of the magnetic head on the magnetic disk more precise. However, in case that the head-actuator arm is merely turned by the VCM to position the magnetic head, the positioning of the magnetic head cannot be made precise so much.
Japanese patent publication 2002-324374A discloses a technology of finely displacing a magnetic head (micro-displacement mechanism). According to this technology, a slider support plate with a slider mounted thereon is supported to be able to turn by elastic hinge sections and thin-film piezoelectric elements, which are provided at the top end section of a head-actuator arm for applying a turning force to the slider support plate so as to position the magnetic head with high precision.
FIG. 22a shows the structure of the micro-displacement mechanism described in Japanese patent publication 2002-324374A, and FIG. 22b explains the displacement operation in this micro-displacement mechanism.
As shown in FIG. 22a, in this micro-displacement mechanism, first and second thin-film piezoelectric elements 221a and 221b are mounted on first and second piezoelectric-body support sections 220a and 220b of a flexible wiring substrate, respectively. The first and second piezoelectric-body support sections 220a and 220b are connected to a slider support plate 220e through, respectively, elastic hinge sections 220c and 220d, each having a slender shape in the middle. The slider support plate 220e is configured to turn around a fulcrum protrusion 222, and a slider 224 having a magnetic head 223 is fixed on the slider support plate 220e. 
As shown in FIG. 22b diagrammatically, the first piezoelectric-body support section 220a and the first thin-film piezoelectric element 221a constitute a first beam B1, and the second piezoelectric-body support section 220b and the second thin-film piezoelectric element 221b constitute a second beam B2. The top end section of the slider support plate 220e constitutes a link L, the fulcrum protrusion 222 constitutes a turning center O, and the slider 224 constitutes an arm A1 integrated with the link L having a length of d, and the head element 223 exists at the top end of the arm A1. The link L is capable of rotating or turning relatively to the first beam B1 and the second beam B2 at its both ends. The reason for the first and second beams B1 and B2 being capable of turning at their tops comes from existence of the elastic hinge sections 220c and 220d. The elastic hinge sections 220c and 220d constitute swing fulcrums C1 and C2, respectively. The elastic hinge sections 220c and 220d have a structure flexible both in a pitching direction and a rolling direction, which can give to the slider 224 excellent flying characteristics above the magnetic disk.
Japanese patent publication 2008-293636A discloses a technology of preventing deformation of a suspension and separation from a dimple (fulcrum protrusion) during manufacturing processes or when an impact is applied. In this technology, an outrigger composed of a pair of rigid beams and a pair of spring beams is provided for supporting a slider support plate, in a micro-displacement mechanism similar to that of Japanese patent publication 2002-324374A.
Japanese patent publication 2001-052456A discloses another technology of finely displacing a magnetic head for positioning the magnetic head with high precision. According to this technology, a pair of plate-shaped arm parts each composed of a plate-shaped elastic body are provided at the top end section of a load beam also composed of a plate-shaped elastic body for supporting a slider mounting part, and piezoelectric thin films provided on the pair of plate-shaped arm parts are driven.
However, according to the micro-displacement mechanism disclosed in Japanese patent publication 2002-324374A, the following problems may arise when performing loading operation in which the slider 224 moves above the magnetic disk and unloading operation in which the slider 224 saves from the magnetic disk.
At the time of the loading operation and the unloading operation of the slider, it is necessary that an attitude angle of the slider, that is, the attitude angle in the rolling direction and the pitching direction has to be set precisely. However, since the elastic hinge sections 220c and 220d in the micro-displacement mechanism of Japanese patent publication 2002-324374A are composed of wiring members and coating resin, these elastic hinge sections are easily deformed although they are flexible. Therefore, it has been difficult to ensure stability in fine adjustment of the attitude angle of the slider, and to regulate this attitude angle. Moreover, because the preload or internal force of pushing the slider support plate with the mounted slider against the fulcrum protrusion is small, the slider support plate is easily separated from the fulcrum protrusion, resulting in possibility that the attitude angle of the slider may become unstable at the time of loading operation and unloading operation and that the magnetic disk may be damaged.
According to the micro-displacement mechanism disclosed in Japanese patent publication 2008-293636A, by providing springy outriggers, deformation of suspension and separation from the dimple can be prevented, but at the same time the outriggers will restrict the micro-displacement operation of the slider, to spoil displacement performance of the head. Furthermore, since the outriggers have to be spring-deformed when turn the slider, required is to provide a large driving force.
Whereas according to the micro-displacement mechanism disclosed in Japanese patent publication 2001-052456A, since the slider is supported only by a pair of plate-shaped arm parts made of an elastic material, the bending rigidity of the elastic material becomes larger than that of the piezoelectric element and therefore it is impossible to obtain sufficient displacement. Also, it is difficult to stably keep the attitude angle of the slider at the time of loading operation and unloading operation.